Effective processes to remove surrounding media from sample pellets (i.e., biological and non-biological) generally involve aspiration of the surrounding media and then, resuspension of the sample pellet while in the same tube with desired solution. Although such processes are effective at removing the majority of surrounding media, residual media remains on the sides of the tube and directly above the pellet surface resulting in the risk of contamination of the pellet with surrounding media upon pellet removal or pellet resuspension.
In addition, direct sample pellet extraction in the presence of the surrounding media requires the pellet to pass through the surrounding media, again, increasing the risk of pellet contamination. For example, a great risk exists concerning transmission of pathogenic agents in biological samples, such as seminal fluid. Semen samples obtained from men infected with pathogens such as HIV and Hepatitis B and C if not decontaminated prior to being used in artificial insemination, in vitro fertilization, or other assisted reproductive technology, may result in the infectious agents being transmitted to the mother, unborn child or health care workers handling the contaminated semen samples. Further, similar risks exist in animal or livestock industries which are utilizing assisted reproductive technology. In livestock, for example, the foot-and-mouth disease virus and porcine reproductive and respiratory syndrome (PRRS) virus have been shown to have devastating consequences to the national and international agricultural economies. As a result of such disease outbreaks, stricter regulations and sometimes bans on importation of animals or semen have been enacted which, in turn, affect animal and livestock industries by cutting off supplies and sources of new genetic materials.
There are currently no methods or apparatus for performance of these methods available that allow direct removal of a biological or non-biological sample pellet without first removing the surrounding media by aspiration or re-exposing the sample pellet to said media. As stated previously, such techniques are inherently flawed because of the likelihood of transferring contaminating agents in the surrounding media back to the sample pellets (e.g., directly from the pipette or indirectly from contaminated materials running down the side of the tube during aspiration).
It became known that such a process and apparatus would be desirable on September 24, 1999 at the Wild Cattle and Buffalo Taxon Advisory Group (TAG) meeting that was held at the annual conference of the American Zoo and Aquarium Association (AZA) in Minneapolis, Minn. At that meeting, a call was made for the formation of a task force by reproductive biologists collaborating or working directly with zoos to increase the research and development of assisted reproductive techniques (e.g., artificial insemination and embryo transfer) for non-domestic animals.
The reason for the alarm was due to the news of the possible closure of the last quarantine station available to animals which are to be exported from Africa and Asia after serving the USDA-mandated quarantine period (60 days outside the United States followed by 30 days within the United States). The station is in Poland and news that this country was going to join the European Union meant that they would be required to follow German guidelines which, consequently, would prohibit the entry of these animals to the quarantine station. Thus, it was hypothesized that assisted reproductive technology would become the only method by which the USDA Animal and Plant Health Inspection Service (APHIS) would allow importation of new genetic lines for captive ungulates (hoofed species such as antelope, deer, buffalo, and the like) and suids (exotic pig species) into American zoos.
At the meeting it was recognized that effective processes and apparatus to perform such processes to reduce or eliminate contamination in sperm samples which do not result in damage to the sperm are not currently available. As a result, the decision was made to focus more research on pathogen (e.g., microorganisms and viruses that create disease) interactions with the spermatozoa and embryos of wildlife species.
It was realized that there had been significant progress on developing methods for “disinfecting” embryos of specific pathogens. Such studies had a direct effect on the OIE and, as a consequence, the USDA APHIS, in lowering restrictions for the international movement of embryos, so long as the IETS HASAC guidelines were followed for proper embryo handling and treatment. See Manual of the International Embryo Transfer Society: A Procedural Guide and General Information for the Use of Embryo Transfer Technology Emphasizing Sanitary Procedures (3rd Edition), D. A. Stringfellow and S. M. Seidel, Editors, IETS, Savoy, Ill., USA, which is herein incorporated by reference in its entirety. Although these procedures exist to reduce or eliminate contamination in oocytes and embryos, which are beneficial to preventing the spread of pathogenic agents, these procedures are not appropriate for use with various other media, such as seminal fluid. First, oocytes have a protective coating, the zona pellucida, which protects the oocytes from the damaging effects of the pathogen reducing or eliminating procedures. Sperm do not have a similar protective coating and thus, may be damaged by the current procedures. Second, oocytes and embryos are relatively large in size (typically on the order of 100 micrometers in diameter) which allows such entities to be handled individually and treated (or “dipped”) in a decontamination solution. In contrast, sperm cannot be handled individually because of size limitations (the diameter of sperm heads are typically less than 5 micrometers).
Therefore, it would be desirable to provide a process and an apparatus which would enable one to remove a biological or non-biological sample pellet directly from a tube containing a sample including the pellet and additional media, without disturbing the surrounding media. More specifically, it would be desirable to provide a process and apparatus to allow pathogenic agents such as viruses, bacteria, and other microorganisms to be removed from seminal fluid samples which did not result in damage to the sperm and allowed the sperm to be extracted with a reduced or eliminated risk of re-contamination by contact between the sperm and the pathogenic agents.